| Named By: | Rainer Zangerl in 1953 |
| Time Period: | Early Cretaceous-Late Cretaceous,[1][2] 120-70 Ma |
| Location: | USA - Alabama - Selma Formation |
| Size: | Around 30 centimetres long |
| Diet: | Omnivore |
| Fossil(s): | At least two specimens |
| Classification: | | Chordata | Reptilia | Testudines | Cryptodira | Protostegidae | Chelospharginae | |
Protostegidae is a family of extinct marine turtles that lived during the Cretaceous period. The family includes some of the largest sea turtles that ever existed. The largest, Archelon, had a head one metre (39 in) long. Like most sea turtles, they had flattened bodies and flippers for front appendages; protostegids had minimal shells like leatherback turtles of modern times.